The 920–900 Ma Bahia-Gangila LIP of the São Francisco and Congo cratons and link with Dashigou-Chulan LIP of North China craton: New insights from U-Pb geochronology and geochemistry
A widespread mafic sill and dyke unit (the Pedro Lessa suite) adjacent to the southeastern São Francisco (SF) craton (eastern South America) is dated as 940 ± 42 Ma, 912 ± 17 Ma, and 986 ± 64 Ma (based on combined ID-TIMS and LA-ICPMS analyses on baddeleyite grains) on the Santa Maria de Itabira gabbroic intrusion. These ages suggest membership in the previously defined ca. 920–900 Ma Large Igneous Province (LIP) (herein referred to as the Bahia-Gangila LIP) of the reconstructed São Francisco and formerly adjacent Congo craton (Africa). Additional mafic and felsic units throughout the SF craton are also linked (based on a literature review), thus expanding the size of the reconstructed LIP to ca. 1,500,000 km2. Geochemistry reveals high Ti OIB signature for most units and low Ti E-MORB composition for the Gangila flood basalts, marking the initiation of attempted ocean opening. Geochemistry of the Bahia-Gangila LIP is also compared with the ca. 920–900 Ma Dashigou-Chulan LIP of the North China craton, and implications for three possible reconstructions of SF/Congo craton with the North China craton are considered.
|Keywords||Geochemistry, Large igneous province, North China craton, São Francisco/Congo craton, U-Pb|
Chaves, A.D.O. (Alexandre de Oliveira), Ernst, R.E, Söderlund, U. (Ulf), Wang, X. (Xinping), & Naeraa, T. (Tomas). (2018). The 920–900 Ma Bahia-Gangila LIP of the São Francisco and Congo cratons and link with Dashigou-Chulan LIP of North China craton: New insights from U-Pb geochronology and geochemistry. Precambrian Research. doi:10.1016/j.precamres.2018.08.023